The parent invention relates to a device which represents an improvement over presently existing marking pens provided with a fine pen-tip, and more specifically with an ultra-fine pen-tip.
In the Japanese Utility Model Laid-Open No. 54-151438 there is disclosed a marking pen having a pen-tip to be extended out of the pen holder in which the pen-tip is slidably arranged with respect to the holder, and the length of the pen-tip projected from the extreme end of the holder is adjustable at its free position and the pen-tip fixed to the cylinder of ink. The same device as described above in Japanese Utility Model Laid-Open No. 55-10789.
In Japanese Utility Model Laid-Open Nos. 55-5241, 55-5242 and 55-23778 and the product of ZEBRA MILLI GRAPH sold by Zebra Co., Ltd. there is disclosed a stationery device in which pen-tips are slidably arranged with respect to the holder and the pen-tips are fixed to the cylinder of ink.
In Japanese Utility Model Laid-Open No. 55-5268 there is proposed a stationary cylinder in which the holder is axially and movably connected to the cylinder, the pen-tip is slidably provided with respect to the holder above and the pen-tip is fixed to the cylinder of ink.
In Japanese Utility Model Laid-Open No. 49-1031 and the product having the name of Variograph sold by Rotringwerke of West Germany there is proposed a stationary device in which a holder is axially and movably connected to the cylinder, the pen-tip is slidably provided with respect to the holder, the length of the pen-tip projected from the extreme end of the holder is adjustable to any position and the pen-tip is removably attached to the cylinder.
In the Japanese Utility Model Laid-Open Nos. 47-36529 and 57-9579 etc. there is proposed a stationary device in which the holder is axially and movably connected to the cylinder, the pen-tip is slidably arranged with respect to the holder, the length of the pen-tip projected from the extreme end of the holder is adjustable at any position and the pen-tip is fixed to the cylinder of ink.
In the Japanese Utility Model Laid-Open No. 54-179248 there is proposed a sign-pen in which the holder is axially and movably connected to the cylinder, the pen-tip is slidably arranged with respect to the holder, the length of the pen-tip projected from the extreme end of the holder is adjustable to any position and the pen-tip is fixed to the cylinder.
In reference to publication No. 54-151438 for example, the holder is not axially and movably connected to the cylinder and so the pen-tip may not be removed from the stationary. A transmitting part with respect to writing pressure is not formed at the pen-tip and an accepting part to bear the transmitting part is not formed as a part of the cylinder. Therefore, although the axial movement of the holder may provide for relatively easy and positive handling, this device should move the writing means in an axial direction, so that improper threaded engagement between the writing means and the holer or cylinder may cause the writing means not to move smoothly. When the pen-tip is worn out, the cylinder of ink should be entirely replaced and the volume of ink remaining in the cylinder is lost which makes the product uneconomical. Moreover, since the part for writing pressure transmitting and the writing pressure part are not connected, incomplete fixing means of the pen-tip with respect to the cylinder of ink may cause the pen-tip to be pushed into the cylinder by the writing pressure.
Referring to the above prior art reference No. 55-5241, replacement of the pen-tip itself is impossible, so that when the pen-tip is worn out, the pen-tip should be replaced in its entirety and the volume of ink remaining in the cylinder is lost, and thus the replacement of the cylinder may make the unit uneconomical. In this case, since the part transmitting is not connected at the pen-tip and the part for accepting the writing pressure from the transmitting part is not connected at the cylinder of ink, incomplete fixing for the pen-tip with respect to the cylinder may cause the pen-tip to be slick in the cylinder by writing pressure and mechanical shock.
In the device of publication No. 55-5268, the pen-tip is fixed to the cylinder of ink, so that it has the same problems and disadvantages found in the other prior art references.
Referring the the example of the prior art in publication No. 49-1031, this is a device relating to a sign-pen in which synthetic resin fibers are coated and bundled to form a soft and thick pen-tip to obtain the writing touch of a brush. This prior art relates to a device in which the foundational end of the soft and thick pen-tip exhibiting the writing touch of a brush is held by a very light frictional force between the base end and the hole of small diameter of the threaded cylinder. When the coating around the outer circumferential surface of the pen-tip is broken, with the result that most of the ink is consumed by thick writing, a shortage of ink results and so the position of the neck is adjusted in order that the projected length of the pen-tip does not cause breakage of the coating. A proper setting of the projected length of the pen-tip may not necessarily cause the position of the neck part to be varied. However, this is not a device in which the position of the neck is adjusted in order to adjust the projected length of the pen-tip from the neck at any position. If the soft and thick pen-tip may show the writing touch of a brush, the writing pressure during the writing operation may be dispersed at the extreme end of the pen-tip and may not reach the base end of the pen-tip so that the foundational end of the pen-tip is merely held with a light frictional force between it and the hole of small diameter of the threaded cylinder and it may not be thought to be fastened or supported by the small hole. Since the pen-tip is soft and thick, even if its outer circumferential surface is applied with a coating, a threaded engagement of the neck part with the threaded cylinder, the hole of small diameter may cause a local pressing of the neck and thus the neck is partially deformed. This prior art does not disclose the relation in size between an outer diameter of the pen-tip and an inner diameter of a fixing hole and does not provide a restricting means of an axial fixing position of the pen-tip in the small diameter hole of the threaded cylinder. Thus, if the pen-tip has a larger diameter than that of the fixing hole, insertion of the pen-tip into the fixing hole causes the open end of the fixing hole at the threaded neck part to be expanded in an inverted-conical shape, the neck part may not be threadably engaged and, without the restricting means of the fixing position of the latter, the axial fixing position of the pen-tip is varied for each of the products, with the result that the projected length of the pen-tip is different for each of the products.
Thus, if the fine pen-tip including a ultra-fine pen-tip is supported under a technical concept that the pen-tip of soft and thick fibrous material having the writing touch of a brush as found in the prior art is held by a light frictional force against the threaded cylinder of small diameter, the writing pressure applied to the extreme end of the pen-tip reaches to the foundational end of the pen-tip, so that the pen-tip is pushed into the cylinder of ink under the writing pressure, the pen-tip may not be supported and the writing may not be performed and thus only a non-practical, inferior product results. Therefore, with this prior art, it is impossible to provide a firm support for the above-mentioned pen-tip.
Referring to the above publication No. 47-36529, for example, the prior art has problems similar to that of publication No. 55-5241, due to the fixing of the pen-tip to the cylinder of ink.
In the case of the publication No. 54-179248, the pen-tip is fixedly supported in the cylinder, so that when it is worn out, replacement of the pen-tip itself may not be performed and the total product should be deposited wastefully. Since the pen-tip is made to be fixed by caulking of the cylindrical body, the pen-tip is deformed at the caulked point to cause the inner passage of ink to be narrowed and deformed and to hinder the smooth flow of ink.